U.S. patent application number 12/490111 was filed with the patent office on 2009-12-24 for liquid crystal composition and liquid crystal display device.
This patent application is currently assigned to CHISSO CORPORATION. Invention is credited to Shigeru KIBE, Masayuki SAITO, Hiroyuki TANAKA.
Application Number | 20090314988 12/490111 |
Document ID | / |
Family ID | 41430271 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090314988 |
Kind Code |
A1 |
KIBE; Shigeru ; et
al. |
December 24, 2009 |
LIQUID CRYSTAL COMPOSITION AND LIQUID CRYSTAL DISPLAY DEVICE
Abstract
A liquid crystal composition having a nematic phase that
includes two components, wherein the first component is a specific
five-membered ring compound having a large maximum temperature and
a large dielectric anisotropy and the second component is a
specific compound having a small viscosity, and a liquid crystal
display device containing the composition.
Inventors: |
KIBE; Shigeru; (Chiba,
JP) ; SAITO; Masayuki; (Chiba, JP) ; TANAKA;
Hiroyuki; (Chiba, JP) |
Correspondence
Address: |
HOGAN & HARTSON L.L.P.
1999 AVENUE OF THE STARS, SUITE 1400
LOS ANGELES
CA
90067
US
|
Assignee: |
CHISSO CORPORATION
Osaka
JP
CHISSO PETROCHEMICAL CORPORATION
Tokyo
JP
|
Family ID: |
41430271 |
Appl. No.: |
12/490111 |
Filed: |
June 23, 2009 |
Current U.S.
Class: |
252/299.63 ;
252/299.66 |
Current CPC
Class: |
Y10T 428/10 20150115;
C09K 2019/3422 20130101; C09K 19/3066 20130101; C09K 2323/00
20200801; C09K 2019/3016 20130101; C09K 2019/0466 20130101; C09K
2019/3019 20130101; C09K 19/3402 20130101; C09K 19/42 20130101 |
Class at
Publication: |
252/299.63 ;
252/299.66 |
International
Class: |
C09K 19/30 20060101
C09K019/30; C09K 19/12 20060101 C09K019/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2008 |
JP |
2008-164198 |
Claims
1. A liquid crystal composition having a nematic phase comprising
two components, wherein the first component is at least one
compound selected from the group of compounds represented by
formulas (1-1) and (1-2); and the second component is at least one
compound selected from the group of compounds represented by
formula (2): ##STR00026## wherein R.sup.1 is alkyl having 1 to 12
carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12
carbons; R.sup.2 and R.sup.3 are each independently alkyl having 1
to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to
12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary
hydrogen is replaced by fluorine; ring A, ring B and ring C are
each independently 1,4-cyclohexylene, 1,4-phenylene,
1,3-dioxane-2,5-diyl, 2-fluoro-1,4-phenylene,
3-fluoro-1,4-phenylene, or 3,5-difluoro-1,4-phenylene; ring D, ring
E and ring F are each independently 1,4-cyclohexylene,
1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
2,5-difluoro-1,4-phenylene; Z.sup.1, Z.sup.2 and Z.sup.3 are each
independently a single bond, ethylene or carbonyloxy; X.sup.1 and
X.sup.2 are each independently hydrogen or fluorine; Y.sup.1 is
fluorine, chlorine or trifluoromethoxy; and m is 0 or 1.
2. The liquid crystal composition according to claim 1, wherein the
first component is at least one compound selected from the group of
compounds represented by formulas (1-1-1) to (1-1-4) and (1-2-1).
##STR00027## wherein R.sup.1 is alkyl having 1 to 12 carbons,
alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons;
X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7, and
X.sup.8 are each independently hydrogen or fluorine; and Y.sup.1 is
fluorine, chlorine or trifluoromethoxy.
3. The liquid crystal composition according to claim 2, wherein the
first component is at least one compound selected from the group of
compounds represented by formulas (1-1-1), (1-1-2) and (1-2-1).
4. The liquid crystal composition according to claim 1, wherein the
second component is at least one compound selected from the group
of compounds represented by formulas (2-1) to (2-6). ##STR00028##
wherein R.sup.2 and R.sup.3 are each independently alkyl having 1
to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to
12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary
hydrogen is replaced by fluorine.
5. The liquid crystal composition according to claim 4, wherein the
second component is at least one compound selected from the group
of compounds represented by formula (2-1).
6. The liquid crystal composition according to claim 4, wherein the
second component is a mixture of at least one compound selected
from the group of compounds represented by formula (2-1) and at
least one compound selected from the group of compounds represented
by formula (2-4).
7. The liquid crystal composition according to claim 4, wherein the
second component is a mixture of at least one compound selected
from the group of compounds represented by formula (2-1), at least
one compound selected from the group of compounds represented by
formula (2-4), and at least one compound selected from the group of
compounds represented by formula (2-6)
8. The liquid crystal composition according to claim 1, wherein the
ratio of the first component is in the range of approximately 5% to
approximately 25% by weight, and the ratio of the second component
is in the range of approximately 40% to approximately 85% by
weight, based on the total weight of the liquid crystal
composition.
9. The liquid crystal composition according to claim 1, wherein the
composition further includes at least one compound selected from
the group of compounds represented by formula (3) as the third
component. ##STR00029## wherein R.sup.1 is alkyl having 1 to 12
carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12
carbons; ring G is independently 1,4-cyclohexylene,
1,3-dioxane-2,5-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene,
3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, or
2,5-pyrimidine; Z.sup.4 is independently a single bond, ethylene,
carbonyloxy, or difluoromethyleneoxy; X.sup.1 and X.sup.2 are each
independently hydrogen or fluorine; Y.sup.1 is fluorine, chlorine,
or trifluoromethoxy; and n is 1, 2 or 3.
10. The liquid crystal composition according to claim 9, wherein
the third component is at least one compound selected from the
group of compounds represented by formulas (3-1) to (3-17):
##STR00030## ##STR00031## wherein R.sup.4 is alkyl having 1 to 12
carbons or alkenyl having 2 to 12 carbons.
11. The liquid crystal composition according to claim 10, wherein
the third component is at least one compound selected from the
group of compounds represented by formula (3-9).
12. The liquid crystal composition according to claim 10, wherein
the third component is at least one compound selected from the
group of compounds represented by formula (3-11).
13. The liquid crystal composition according to claim 10, wherein
the third component is at least one compound selected from the
group of compounds represented by formula (3-17).
14. The liquid crystal composition according to claim 10, wherein
the third component is a mixture of at least one compound selected
from the group of compounds represented by formula (3-6) and at
least one compound selected from the group of compounds represented
by formula (3-11).
15. The liquid crystal composition according to claim 10, wherein
the third component is a mixture of at least one compound selected
from the group of compounds represented by formula (3-9) and at
least one compound selected from the group of compounds represented
by formula (3-11).
16. The liquid crystal composition according to claim 10, wherein
the third component is a mixture of at least one compound selected
from the group of compounds represented by formula (3-11) and at
least one compound selected from the group of compounds represented
by formula (3-17).
17. The liquid crystal composition according to claim 9, wherein
the ratio of the third component is in the range of approximately
5% to approximately 60% by weight based on the total weight of the
liquid crystal composition.
18. The liquid crystal composition according to claim 1, wherein
the composition has a maximum temperature of a nematic phase of
approximately 70.degree. C. or more, an optical anisotropy
(25.degree. C.) at a wavelength of 589 nm of approximately 0.08 or
more, and a dielectric anisotropy (25.degree. C.) at a frequency of
1 kHz of approximately 2 or more.
19. A liquid crystal display device that includes the liquid
crystal composition according to claim 1.
20. The liquid crystal display device according to claim 19,
wherein the operation mode of the liquid crystal display device is
a TN mode, an OCB mode, an IPS mode, or a PSA mode, and the driving
mode of the liquid crystal display device is an active matrix mode.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn. 119
to Japanese Patent Application No. 2008-164198, filed Jun. 24,
2008, which application is expressly incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates mainly to a liquid crystal composition
suitable for use in an active matrix (AM) device, and an AM device
containing the composition. The invention relates particularly to a
liquid crystal composition having a positive dielectric anisotropy,
and to a device of a twisted nematic (TN) mode, an optically
compensated bend (OCB) mode, an in-plane switching (IPS) mode or a
polymer sustained alignment (PSA) mode containing the
composition.
[0004] 2. Related Art
[0005] In a liquid crystal display device, a classification based
on the operation mode of liquid crystals includes phase change
(PC), twisted nematic (TN), super twisted nematic (STN),
electrically controlled birefringence (ECB), optically compensated
bend (OCB), in-plane switching (IPS), vertical alignment (VA),
polymer sustained alignment (PSA), and so forth. A classification
based on a driving mode includes a passive matrix (PM) and an
active matrix (AM). The PM is further classified into static,
multiplex and so forth, and the AM is further classified into a
thin film transistor (TFT), a metal-insulator-metal (MIM) and so
forth. The TFT is further classified into amorphous silicon and
polycrystal silicon. The latter is classified into a
high-temperature type and a low-temperature type according to a
production process. A classification based on a light source
includes a reflection type utilizing natural light, a transmission
type utilizing a backlight, and a semi-transmission type utilizing
both the natural light and the backlight.
[0006] These devices contain a liquid crystal composition having
suitable characteristics. The liquid crystal composition has a
nematic phase. General characteristics of the composition should be
improved to obtain an AM device having good general
characteristics. Table I below summarizes a relationship between
the general characteristics of the two. The general characteristics
of the composition will be explained further based on a
commercially available AM device. A temperature range of a nematic
phase relates to a temperature range in which the device can be
used. A desirable maximum temperature of the nematic phase is
approximately 70.degree. C. or more and a desirable minimum
temperature is approximately -10.degree. C. or less. The viscosity
of the composition relates to the response time of the device. A
short response time is desirable for displaying moving images with
the device. Accordingly, a small viscosity of the composition is
desirable. A small viscosity at a low temperature is more
desirable.
TABLE-US-00001 TABLE 1 General Characteristics of Liquid Crystal
Composition and AM Device General Characteristics of a General No.
Composition Characteristics of an AM Device 1 Temperature range of
a Usable temperature range is wide nematic phase is wide 2
Viscosity is small.sup.1) Response time is short 3 Optical
anisotropy is suitable Contrast ratio is large 4 Dielectric
anisotropy is Driving voltage is low and electric positively or
negatively large power consumption is small Contrast ratio is large
5 Specific resistance is large Voltage holding ratio is large and a
contrast ratio is large 6 It is stable to ultraviolet light Service
life is long and heat .sup.1)A liquid crystal composition can be
injected into a cell in a short time.
[0007] The optical anisotropy of the composition relates to the
contrast ratio of the device. The product (.DELTA.n.times.d) of the
optical anisotropy (.DELTA.n) of the composition and the cell gap
(d) of the device is designed in order to maximize the contrast
ratio. A suitable value of the product depends on the kind of
operation modes. In a device having a TN mode or the like, a
suitable value is approximately 0.45 .mu.m. In this case, a
composition having a large optical anisotropy is desirable for a
device having a small cell gap. A large dielectric anisotropy of
the composition contributes to a low threshold voltage, a small
electric power consumption and a large contrast ratio. Accordingly,
a large dielectric anisotropy is desirable. A large specific
resistance of the composition contributes to a large voltage
holding ratio and a large contrast ratio of the device.
Accordingly, a composition having a large specific resistance is
desirable at room temperature and also at a high temperature in the
initial stage. A composition having a large specific resistance is
desirable at room temperature and also at a high temperature after
it has been used for a long time. The stability of the composition
to ultraviolet light and heat relates to the service life of the
liquid crystal display device. In the case where the stability is
high, the device has a long service life. These characteristics are
desirable for an AM device used in a liquid crystal projector, a
liquid crystal television and so forth.
[0008] A composition having a positive dielectric anisotropy is
used for an AM device having a TN mode. On the other hand, a
composition having a negative dielectric anisotropy is used for an
AM device having a VA mode. A composition having a positive or
negative dielectric anisotropy is used for an AM device having an
IPS mode. A composition having a positive or negative dielectric
anisotropy is used for an AM device having a PSA mode. Examples of
the liquid crystal composition having a positive dielectric
anisotropy are disclosed in the following patent documents.
[0009] EP 1,482,019 A (2004), WO 2004/048501.cndot.A, WO
2005/019378 A, WO 2005/019381 A, WO 2006/125511 A, WO 1996/11897 A,
and JP 2003-176251 A (2003).
[0010] A desirable AM device is characterized as having a usable
temperature range that is wide, response time that is short, a
contrast ratio that is large, threshold voltage that is low, a
voltage holding ratio that is large, a service life that is long,
and so forth. Even one millisecond shorter response time is
desirable. Thus, a composition having characteristics such as a
high maximum temperature of a nematic phase, a low minimum
temperature of a nematic phase, a small viscosity, a large optical
anisotropy, a large dielectric anisotropy, a large specific
resistance, a high stability to ultraviolet light, a high stability
to heat, and so forth is especially desirable.
SUMMARY OF THE INVENTION
[0011] The invention concerns a liquid crystal composition having a
nematic phase that includes two components, wherein the first
component is at least one compound selected from the group of
compounds represented by formulas (1-1) and (1-2), and the second
component is at least one compound selected from the group of
compounds represented by formula (2):
##STR00001##
wherein R.sup.1 is alkyl having 1 to 12 carbons, alkoxy having 1 to
12 carbons or alkenyl having 2 to 12 carbons; R.sup.2 and R.sup.3
are each independently alkyl having 1 to 12 carbons, alkoxy having
1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having
2 to 12 carbons in which arbitrary hydrogen is replaced by
fluorine; ring A, ring B and ring C are each independently
1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl,
2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
3,5-difluoro-1,4-phenylene; ring D, ring E and ring F are each
independently 1,4-cyclohexylene, 1,4-phenylene,
2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
2,5-difluoro-1,4-phenylene; Z.sup.1, Z.sup.2 and Z.sup.3 are each
independently a single bond, ethylene or carbonyloxy; X.sup.1 and
X.sup.2 are each independently hydrogen or fluorine; Y.sup.1 is
fluorine, chlorine or trifluoromethoxy; and m is 0 or 1.
[0012] The invention also concerns a liquid display device that
includes the liquid crystal composition, and so forth.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The terms used in the specification and claims are defined
as follows. The liquid crystal composition and/or the liquid
crystal display device of the invention may occasionally be
expressed simply as "the composition" or "the device,"
respectively. A liquid crystal display device is a generic term for
a liquid crystal display panel and a liquid crystal display module.
The "liquid crystal compound" is a generic term for a compound
having a liquid crystal phase such as a nematic phase and a smectic
phase, and also for a compound having no liquid crystal phase but
being useful as a component of a composition. The useful compound
contains a 6-membered ring such as 1,4-cyclohexylene and
1,4-phenylene, and its molecular structure is rod-like. An
optically active compound or a polymerizable compound may
occasionally be added to the composition. Even in the case where
the compound is a liquid crystal compound, the compound is
classified into an additive herein. At least one compound selected
from the group of compounds represented by formula (1-1) may be
abbreviated to "the compound (1-1)." "The compound (1-1)" means one
compound or two or more compounds represented by formula (1-1). The
other formulas are applied with the same rules. The term
"arbitrary" indicates that both the position and the number are
arbitrary, excluding the case where the number is 0.
[0014] A higher limit of a temperature range of a nematic phase may
be abbreviated to "a maximum temperature." A lower limit of a
temperature range of a nematic phase may be abbreviated to "a
minimum temperature." "A specific resistance is large" means that
the composition has a large specific resistance at room temperature
and also at a high temperature close to the maximum temperature of
the nematic phase in the initial stage, and that the composition
has a large specific resistance at room temperature and also at a
high temperature close to the maximum temperature of the nematic
phase even after it has been used for a long time. "A voltage
holding ratio is large" means that a device has a large voltage
holding ratio at room temperature and also at a high temperature
close to the maximum temperature of a nematic phase in the initial
stage, and that the device has a large voltage holding ratio at
room temperature and also at a high temperature close to the
maximum temperature of the nematic phase even after it has been
used for a long time. In the description of the characteristics
such as the optical anisotropy, measured values obtained by the
methods disclosed in Examples are used. The first component is one
compound or two or more compounds. "A ratio of the first component"
means the percentage by weight (% by weight) based on the total
weight of a liquid crystal composition. A ratio of the second
component and so forth are applied with the same rule. A ratio of
an additive mixed with the composition means the percentage by
weight (% by weight) based on the total weight of a liquid crystal
composition.
[0015] The symbol R.sup.1 was used for a plurality of compounds in
the chemical formulas for component compounds. In these compounds,
two arbitrary R.sup.1 may be identical or different. In one case,
for example, R.sup.1 of the compound (1-1) is ethyl and R.sup.1 of
the compound (1-2) is ethyl. In another case, R.sup.1 of the
compound (1-1) is ethyl and R.sup.1 of the compound (1-2) is
propyl. The same rule applies to R.sup.2, R.sup.3, and so forth.
"CL" in the chemical formulas represents chlorine.
[0016] One of the advantages of the invention is to provide a
liquid crystal composition that satisfies at least one
characteristic among the characteristics such as a high maximum
temperature of a nematic phase, a low minimum temperature of a
nematic phase, a small viscosity, a large optical anisotropy, a
large dielectric anisotropy, a large specific resistance, a high
stability to ultraviolet light, and a high stability to heat.
Another of the advantages of the invention is to provide a liquid
crystal composition that is properly balanced regarding at least
two characteristics. Another of the advantages of the invention is
to provide a liquid crystal display device that contains the
composition. Another of the advantages of the invention is to
provide a composition that has a large optical anisotropy, a large
dielectric anisotropy, a high stability to ultraviolet light and so
forth, and to provide an AM device that has a short response time,
a large voltage holding ratio, a large contrast ratio, a long
service life and so forth.
[0017] The liquid crystal composition of the invention satisfied at
least one characteristics among the characteristics such as a high
maximum temperature of a nematic phase, a low minimum temperature
of a nematic phase, a small viscosity, a large optical anisotropy,
a large dielectric anisotropy, a large specific resistance, a high
stability to ultraviolet radiation, an a high stability to heat.
The liquid crystal composition was properly balanced regarding at
least two characteristics. The liquid crystal display device
contained the composition. The composition had a large optical
anisotropy, a large dielectric anisotropy, a high stability to
ultraviolet light and so forth, and the AM device had a short
response time, a large voltage holding ratio, a large contrast
ratio, a long service life and so forth.
[0018] The invention has the following features:
[0019] Item 1. A liquid crystal composition having a nematic phase
that includes two components, wherein the first component is at
least one compound selected from the group of compounds represented
by formulas (1-1) and (1-2), and the second component is at least
one compound selected from the group of compounds represented by
formula (2):
##STR00002##
wherein R.sup.1 is alkyl having 1 to 12 carbons, alkoxy having 1 to
12 carbons or alkenyl having 2 to 12 carbons; R.sup.2 and R.sup.3
are each independently alkyl having 1 to 12 carbons, alkoxy having
1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having
2 to 12 carbons in which arbitrary hydrogen is replaced by
fluorine; ring A, ring B and ring C are each independently
1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl,
2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
3,5-difluoro-1,4-phenylene; ring D, ring E and ring F are each
independently 1,4-cyclohexylene, 1,4-phenylene,
2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
2,5-difluoro-1,4-phenylene; Z.sup.1, Z.sup.2 and Z.sup.3 are each
independently a single bond, ethylene or carbonyloxy; X.sup.1 and
X.sup.2 are each independently hydrogen or fluorine; Y.sup.1 is
fluorine, chlorine or trifluoromethoxy; and m is 0 or 1.
[0020] Item 2. The liquid crystal composition according to item 1,
wherein the first component is at least one compound selected from
the group of compounds represented by formulas (1-1-1) to (1-1-4)
and (1-2-1).
##STR00003##
wherein R.sup.1 is alkyl having 1 to 12 carbons, alkoxy having 1 to
12 carbons or alkenyl having 2 to
[0021] 12 carbons; X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5,
X.sup.6, X.sup.7, and X.sup.8 are each independently hydrogen or
fluorine; and Y.sup.1 is fluorine, chlorine or
trifluoromethoxy.
[0022] Item 3. The liquid crystal composition according to item 2,
wherein the first component is at least one compound selected from
the group of compounds represented by formulas (1-1-1), (1-1-2) and
(1-2-1).
[0023] Item 4. The liquid crystal composition according to any one
of items 1 to 3, wherein the second component is at least one
compound selected from the group of compounds represented by
formulas (2-1) to (2-6).
##STR00004##
wherein R.sup.2 and R.sup.3 are each independently alkyl having 1
to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to
12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary
hydrogen is replaced by fluorine.
[0024] Item 5. The liquid crystal composition according to item 4,
wherein the second component is at least one compound selected from
the group of compounds represented by formula (2-1).
[0025] Item 6. The liquid crystal composition according to item 4,
wherein the second component is a mixture of at least one compound
selected from the group of compounds represented by formula (2-1)
and at least one compound selected from the group of compounds
represented by formula (2-4).
[0026] Item 7. The liquid crystal composition according to item 4,
wherein the second component is a mixture of at least one compound
selected from the group of compounds represented by formula (2-1),
at least one compound selected from the group of compounds
represented by formula (2-4), and at least one compound selected
from the group of compounds represented by formula (2-6).
[0027] Item 8. The liquid crystal composition according to any one
of items 1 to 7, wherein the ratio of the first component is in the
range of approximately 5% to approximately 25% by weight, and the
ratio of the second component is in the range of approximately 40%
to approximately 85% by weight, based on the total weight of the
liquid crystal composition.
[0028] Item 9. The liquid crystal composition according to any one
of items 1 to 8, wherein the composition further includes at least
one compound selected from the group of compounds represented by
formula (3) as the third component.
##STR00005##
wherein R.sup.1 is alkyl having 1 to 12 carbons, alkoxy having 1 to
12 carbons or alkenyl having 2 to 12 carbons; ring G is
independently 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl,
1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene,
3,5-difluoro-1,4-phenylene, or 2,5-pyrimidine; Z.sup.4 is
independently a single bond, ethylene, carbonyloxy, or
difluoromethyleneoxy; X.sup.1 and X.sup.2 are each independently
hydrogen or fluorine; Y.sup.1 is fluorine, chlorine, or
trifluoromethoxy; and n is 1, 2 or 3.
[0029] Item 10. The liquid crystal composition according to item 9,
wherein the third component is at least one compound selected from
the group of compounds represented by formulas (3-1) to (3-17).
##STR00006## ##STR00007##
wherein R.sup.4 is alkyl having 1 to 12 carbons or alkenyl having 2
to 12 carbons.
[0030] Item 11. The liquid crystal composition according to item
10, wherein the third component is at least one compound selected
from the group of compounds represented by formula (3-9).
[0031] Item 12. The liquid crystal composition according to item
10, wherein the third component is at least one compound selected
from the group of compounds represented by formula (3-11).
[0032] Item 13. The liquid crystal composition according to item
10, wherein the third component is at least one compound selected
from the group of compounds represented by formula (3-17).
[0033] Item 14. The liquid crystal composition according to item
10, wherein the third component is a mixture of at least one
compound selected from the group of compounds represented by
formula (3-6) and at least one compound selected from the group of
compounds represented by formula (3-11).
[0034] Item 15. The liquid crystal composition according to item
10, wherein the third component is a mixture of at least one
compound selected from the group of compounds represented by
formula (3-9) and at least one compound selected from the group of
compounds represented by formula (3-11).
[0035] Item 16. The liquid crystal composition according to item
10, wherein the third component is a mixture of at least one
compound selected from the group of compounds represented by
formula (3-11) and at least one compound selected from the group of
compounds represented by formula (3-17).
[0036] Item 17. The liquid crystal composition according to any one
of items 9 to 16, wherein the ratio of the third component is in
the range of approximately 5% to approximately 60% by weight based
on the total weight of the liquid crystal composition.
[0037] Item 18. The liquid crystal composition according to any one
of items 1 to 17, wherein the composition has a maximum temperature
of a nematic phase of approximately 70.degree. C. or more, an
optical anisotropy (25.degree. C.) at a wavelength of 589 nm of
approximately 0.08 or more, and a dielectric anisotropy (25.degree.
C.) at a frequency of 1 kHz of approximately 2 or more.
[0038] Item 19. A liquid crystal display device that includes the
liquid crystal composition according to any one of items 1 to
18.
[0039] Item 20. The liquid crystal display device according to item
19, wherein the operation mode of the liquid crystal display device
is a twisted nematic (TN) mode, an optically compensated bend (OCB)
mode, an in-plane switching (IPS) mode, or a polymer sustained
alignment (PSA) mode, and the driving mode of the liquid crystal
display device is an active matrix mode.
[0040] The invention further includes: (1) the composition
described above, wherein the composition further contains an
optically active compound; (2) the composition described above,
wherein the composition further contains an additive, such as an
antioxidant, an ultraviolet light absorbent, a defoaming agent, a
polymerizable compound, and/or a polymerization initiator; (3) an
AM device containing the composition described above; (4) a device
having a TN, ECB, OCB, IPS, or PSA, containing the composition
described above; (5) a device of a transmission type, containing
the composition described above; (6) use of the composition
described above as a composition having a nematic phase; and (7)
use as an optically active composition by adding an optically
active compound to the composition described above.
[0041] The composition of the invention will be explained in the
following order. First, the constitution of component compounds in
the composition will be explained. Second, the main characteristics
of the component compounds and the main effects of the compounds on
the composition will be explained. Third, the combinations of the
components in the composition, a desirable ratio of the component
compounds, and the basis thereof will be explained. Fourth, a
desirable embodiment of the component compounds will be explained.
Fifth, examples of the component compounds will be shown. Sixth,
additives that may be added to the composition will be explained.
Seventh, the methods for preparing the component compounds will be
explained. Lastly, use of the composition will be explained.
[0042] First, the constitution of component compounds in the
composition will be explained. The composition of the invention is
classified into a composition A and a composition B. The
composition A may further contain other liquid crystal compounds,
an additive, an impurity, and so forth. "The other liquid crystal
compounds" are different from the compound (1-1), the compound
(1-2), the compound (2) and the compound (3). Such compounds are
mixed with the composition for the purpose of adjusting the
characteristics of the composition. The other liquid crystal
compounds desirably contain a smaller amount of a cyano compound
from the viewpoint of stability to heat or ultraviolet light. A
more desirable ratio of the cyano compound is approximately 0% by
weight. The additive includes an optically active compound, an
antioxidant, an ultraviolet light absorbent, a coloring matter, a
defoaming agent, a polymerizable compound, a polymerization
initiator and so forth. The impurity is a compound and so forth
contaminated in a process such as the synthesis of a component
compound and so forth. Even in the case where the compound is a
liquid crystal compound, it is classified into an impurity.
[0043] The composition B is essentially consisting of compounds
selected from the compound (1-1), the compound (1-2), the compound
(2), and the compound (3). The term "essentially" means that the
composition does not contain a liquid crystal compound different
from these compounds. The composition B has fewer components as
compared to the composition A. The composition B is more desirable
than the composition A from the viewpoint of cost reduction. The
composition A is more desirable than the composition B from the
viewpoint that physical properties can be adjusted further by
adding the other liquid crystal compounds.
[0044] Second, the main characteristics of the component compounds
and the main effects of the compounds on the composition will be
explained. The main characteristics of the component compounds are
summarized in Table 2. In Table 2, the symbol L represents large or
high, the symbol M represents a middle degree, and the symbol S
represents small or low. The symbols L, M and S are classifications
based on qualitative comparison among the component compounds and 0
(zero) means the value of dielectric anisotropy is nearly zero
TABLE-US-00002 TABLE 2 Characteristics of Compounds Compound (1-1)
(1-2) (2) (3) Maximum Temperature M M S-L A-M Viscosity L L S-M M-L
Optical Anisotropy M-L M-L S-L M-L Dielectric Anisotropy M-L M-L 0
S-L Specific Resistance L L L L
[0045] The main effects of the component compounds on the
characteristics of the composition upon mixing the component
compounds with the composition are as follows. The compound (1-1)
and the compound (1-2) increase the maximum temperature and
increase the dielectric anisotropy. The compound (2) increases the
maximum temperature or decrease the viscosity. The compound (3)
decreases the minimum temperature and increases the dielectric
anisotropy.
[0046] Third, the combinations of the components in the
composition, desirable ratios of the component compounds, and the
basis thereof will be explained. The combinations of the components
in the composition are first component+second component, and first
component+second component+third component.
[0047] A desirable ratio of the component compounds and the basis
thereof will be explained. A desirable ratio of the first component
is approximately 5% by weight or more for increasing the maximum
temperature and increasing the dielectric anisotropy, and is
approximately 25% by weight or less for decreasing the minimum
temperature. A more desirable ratio is in the range from
approximately 5% to approximately 20% by weight. A particularly
desirable ratio is in the range from approximately 5% to
approximately 15% by weight.
[0048] A desirable ratio of the second component is approximately
40% by weight or more for decreasing the viscosity, and is
approximately 85% by weight or less for increasing the dielectric
anisotropy. A more desirable ratio is in the range from
approximately 45% to approximately 80% by weight. A particularly
desirable ratio is in the range from approximately 50% to
approximately 75% by weight.
[0049] The third component is suitable for preparing a composition
having a particularly large dielectric anisotropy. A desirable
ratio of the component is in the range from approximately 5% to
approximately 60% by weight. A more desirable ratio is in the range
from approximately 10% to approximately 55% by weight. A
particularly desirable ratio is in the range from approximately 15%
to approximately 50% by weight.
[0050] Fourth, a desirable embodiment of the component compounds
will be explained. R.sup.1 is alkyl having 1 to 12 carbons, alkoxy
having 1 to 12 carbons or alkenyl having 2 to 12 carbons. Desirable
R.sup.1 is alkyl having 1 to 12 carbons for increasing the
stability to ultraviolet light or heat. R.sup.2 and R.sup.3 are
each independently alkyl having 1 to 12 carbons, alkoxy having 1 to
12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to
12 carbons in which arbitrary hydrogen is replaced by fluorine.
Desirable R.sup.2 is alkenyl having 2 to 12 carbons for decreasing
the minimum temperature or decreasing the viscosity. Desirable
R.sup.3 is alkyl having 1 to 12 carbons for increasing the
stability to ultraviolet light or heat. R.sup.4 is alkyl having 1
to 12 carbons or alkenyl having 2 to 12 carbons. Desirable R.sup.4
is alkyl having 1 to 12 carbons for increasing the stability to
ultraviolet light or heat.
[0051] Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl,
hexyl, heptyl, or octyl. More desirable alkyl is ethyl, propyl,
butyl, pentyl, or heptyl for decreasing the viscosity.
[0052] Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy,
pentyloxy, hexyloxy, or heptyloxy. More desirable alkoxy is methoxy
or ethoxy for decreasing the viscosity.
[0053] Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl,
1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl,
3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl,
or 5-hexenyl. More desirable alkenyl is vinyl, 1-propenyl,
3-butenyl, or 3-pentenyl for decreasing the viscosity. A desirable
configuration of --CH.dbd.CH-- in these alkenyls depends on the
position of a double bond. Trans is desirable in the alkenyl such
as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl, and
3-hexenyl for decreasing the viscosity. C is desirable in the
alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In these
alkenyls, linear alkenyl is preferable to branched alkenyl.
[0054] Desirable examples of alkenyl in which arbitrary hydrogen is
replaced by fluorine are 2,2-difluorovinyl,
3,3-difluoro-2-propenyl, 4,4-difluoro-3-butenyl,
5,5-difluoro-4-pentenyl, and 6,6-difluoro-5-hexenyl. More desirable
examples are 2,2-difluorovinyl and 4,4-difluoro-3-butenyl for
decreasing the viscosity.
[0055] Ring A, ring B and ring C are each independently
1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl,
2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
3,5-difluoro-1,4-phenylene. Desirable ring A, ring B and ring C are
1,4-cyclohexylene for decreasing the viscosity or
1,3-dioxane-2,5-diyl for increasing the dielectric anisotropy. Ring
D, ring E and ring F are each independently 1,4-cyclohexylene,
1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or
2,5-difluoro-1,4-phenylene. Desirable ring D, ring E and ring F are
1,4-cyclohexylene for decreasing the viscosity or 1,4-phenylene for
increasing the optical anisotropy. Ring G is 1,4-cyclohexylene,
1,3-dioxane-2,5-diyl, 1,4-phenylene, 2-fluoro-1,4-phenylene,
3-fluoro-1,4-phenylene, 3,5-difluoro-1,4-phenylene, or
2,5-pyrimidine. When n is 2 or 3 in the compound (3), any two rings
G may be the same or different. Desirable ring G is 1,4-phenylene
for increasing the optical anisotropy.
[0056] Z.sup.1, Z.sup.2 and Z.sup.3 are each independently a single
bond, ethylene, or carbonyloxy. Desirable Z.sup.1, Z.sup.2 and
Z.sup.3 are a single bond for decreasing the viscosity. Z.sup.4 is
a single bond, ethylene, carbonyloxy, or difluoromethyleneoxy. When
n is 2 or 3 in the compound (3), any two may be the same or
different. Desirable Z.sup.4 is difluoromethyleneoxy for increasing
the dielectric anisotropy.
[0057] X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6,
X.sup.7, and X.sup.8 are each independently hydrogen or fluorine.
Three or more of X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5,
X.sup.6, X.sup.7, and X.sup.8 are desirably fluorine for increasing
the dielectric anisotropy.
[0058] Y.sup.1 is fluorine, chlorine or trifluoromethoxy. Desirable
Y.sup.1 is fluorine for decreasing the minimum temperature.
[0059] The numerical value m is 0 or 1. Desirable m is 0 for
decreasing the viscosity.
[0060] The numerical value n is 1, 2 or 3. Desirable n is 2 for
decreasing the minimum temperature.
[0061] Fifth, examples of the component compounds will be shown. In
the desirable compounds described below, R.sup.5 is linear alkyl
having 1 to 12 carbons. R.sup.6 is linear alkyl having 1 to 12
carbons or linear alkoxy having 1 to 12 carbons. R.sup.7 and
R.sup.8 are each independently linear alkyl having 1 to 12 carbons
or linear alkenyl having 2 to 12 carbons. On the configuration of
1,4-cyclohexylene, trans is preferable to cis for increasing the
maximum temperature.
[0062] Desirable compound (1-1) are the compound (1-1-1-1), the
compounds (1-1-2-1) to (1-1-2-2), the compound (1-1-3-1), and the
compound (1-1-4-1). More desirable compound (1-1) are the compound
(1-1-1-1), the compound (1-1-2-1) and the compound (1-1-3-1).
Especially desirable compound (1-1) are the compound (1-1-1-1) and
the compound (1-1-2-1). Desirable compound (1-2) is the compound
(1-2-1-1). Desirable compound (2) are the compounds (2-1-1) to
(2-6-1). More desirable compound (2) are the compound (2-1-1), the
compound (2-3-1), the compound (2-4-1), and the compound (2-6-1).
Especially desirable compound (2) are the compound (2-1-1), the
compound (2-4-1) and the compound (2-6-1). Desirable compound (3)
are the compounds (3-1-1) to (3-17-1) and compounds (3-18) to
(3-23). More desirable compound (3) are the compound (3-9-1), the
compound (3-11-1) and the compound (3-17-1). Especially desirable
compound (3) are the compounds (3-11-1) and the compound
(3-17-1).
##STR00008## ##STR00009## ##STR00010##
[0063] Sixth, additives capable of being mixed with the composition
will be explained. The additives include an optically active
compound, an antioxidant, an ultraviolet light absorbent, a
coloring matter, a defoaming agent, a polymerizable compound, a
polymerization initiator and so forth. An optically active compound
is mixed in the composition for inducing the helical structure of
liquid crystals to provide a twist angle. Examples of the optically
active compound include the compounds (6-1) to (6-4) below. A
desirable ratio of the optically active compound is approximately
5% by weight or less. A more desirable ratio is in the range from
approximately 0.01% to approximately 2% by weight.
##STR00011##
[0064] An antioxidant is mixed with the composition in order to
avoid a decrease in specific resistance caused by heating in the
air, or to maintain a large voltage holding ratio at room
temperature and also at a high temperature close to the maximum
temperature of the nematic phase even after the device has been
used for a long time.
[0065] Preferred examples of the antioxidant include the compound
(7):
##STR00012##
wherein n is an integer of from 1 to 9. In the compound (7),
desirable n are 1, 3, 5, 7, or 9. More desirable n are 1 or 7. When
n is 1, the compound (7) has a large volatility, and is effective
in preventing the decrease of specific resistance caused by heating
in the air. When n is 7, the compound (7) has a small volatility,
and is effective in maintaining a large voltage holding ratio at
room temperature and also at a high temperature close to the
maximum temperature of the nematic phase even after the device has
been used for a long time. A desirable ratio of the antioxidant is
approximately 50 ppm or more for obtaining the advantage thereof,
and is approximately 600 ppm or less for preventing the maximum
temperature from being decreased and preventing the minimum
temperature from being increased. A more desirable ratio thereof is
in the range from approximately 100 ppm to approximately 300
ppm.
[0066] Preferred examples of the ultraviolet light absorbent
include a benzophenone derivative, a benzoate derivative and a
triazole derivative. A light stabilizer such as amine with steric
hindrance is also desirable. A desirable ratio of the absorbent or
stabilizer is approximately 50 ppm or more for obtaining the
advantage thereof, and is approximately 10,000 ppm or less for
preventing the maximum temperature from being decreased and
preventing the minimum temperature from being increased. A more
desirable ratio thereof is in the range from approximately 100 ppm
to approximately 10,000 ppm.
[0067] A dichroic dye such as an azo dye or an anthraquinone dye is
mixed with the composition to suit for a device of a guest host
(GH) mode. A desirable ratio of the dye is in the range from
approximately 0.01% to approximately 10% by weight. A defoaming
agent such as dimethyl silicone oil or methylphenyl silicone oil is
added to the composition to prevent foaming. A desirable ratio of
the defoaming agent is approximately 1 ppm or more for obtaining
the advantage thereof, and is approximately 1,000 ppm or less for
preventing defective indication. A more desirable ratio thereof is
in the range from approximately 1 ppm to approximately 500 ppm.
[0068] A polymerizable compound is mixed with the composition to
suit for a device of a polymer sustained alignment (PSA) mode.
Preferred examples of the polymerizable compound include a compound
having a polymerizable group, such as acrylate, methacrylate, vinyl
compounds, vinyloxy compounds, propenyl ether, epoxy compounds
(oxirane, oxetane), and vinyl ketone. An especially desirable
example is a derivative of acrylate or methacrylate. A desirable
ratio of the polymerizable compound is approximately 0.05% by
weight or more for obtaining the advantage thereof, and is
approximately 10% by weight or less for preventing defective
displaying. A more desirable ratio thereof is in the range from
approximately 0.1% to approximately 2% by weight. The polymerizable
compound is desirably polymerized by UV irradiation and so forth in
the presence of a suitable initiator such as a photo-polymerization
initiator. Suitable conditions for the polymerization, a suitable
type of initiators and suitable amounts are known to those skilled
in the art, and are described in the literature. For example,
Irgacure 651 (registered trademark), Irgacure 184 (registered
trademark) or Darocure 1173 (registered trademark) (Ciba Japan
K.K.) that are photo-polymerization initiators are suitable for
radical polymerization. The polymerizable compound desirably
contains a photo-polymerization initiator in the range of
approximately 0.1% to approximately 5% by weight. The polymerizable
compound contains especially desirably a photopolymerization
initiator in the range of approximately 1% to approximately 3% by
weight.
[0069] Seventh, the methods for preparing the component compounds
will be explained. These compounds can be prepared by known
methods. The methods for the preparation will be exemplified below.
The compounds (1-1-1-1) and (3-6-1) are prepared by the method
disclosed in JP H10-204016 A (1998). The compounds (2-1-1) and
(2-4-1) are prepared by the method disclosed in JP H4-30382 B
(1992). The compounds (3-5-1) and (3-8-1) are prepared by the
method disclosed in JP H2-233626 A/1990. Antioxidants are
commercially available. The compound of formula (7) wherein n is 1
is commercially available from Sigma-Aldrich Corporation. The
compound (7) wherein n is 7 is prepared according to the method
described in U.S. Pat. No. 3,660,505 (1972).
[0070] The compounds for which preparation methods were not
described above can be prepared according to the methods described
in ORGANIC SYNTHESES (John Wiley & Sons, Inc), ORGANIC
REACTIONS (John Wiley & Sons, Inc), COMPREHENSIVE ORGANIC
SYNTHESIS (Pergamon Press), NEW EXPERIMENTAL CHEMISTRY COURSE (Shin
Jikken Kagaku Kouza) (Maruzen, Inc.), and so forth. The composition
is prepared according to known methods using the compounds thus
obtained. For example, the component compounds are mixed and
dissolved in each other by heating.
[0071] Last, use of the composition will be explained. The
compositions of the invention mainly have a minimum temperature of
approximately -10.degree. C. or less, a maximum temperature of
approximately 70.degree. C. or more, and an optical anisotropy in
the range of approximately 0.07 to approximately 0.20. The device
containing the composition has a large voltage holding ratio. The
composition is suitable for an AM device. The composition is
suitable especially for an AM device of a transmission type. The
composition having an optical anisotropy in the range of
approximately 0.08 to approximately 0.25 and further the
composition having an optical anisotropy in the range of
approximately 0.10 to approximately 0.30 may be prepared by
controlling the ratios of the component compounds or by mixing with
other liquid crystal compounds. The composition can be used as a
composition having a nematic phase and as an optically active
composition by adding an optically active compound.
[0072] The composition can be used for an AM device. It can also be
used for a PM device. The composition can also be used for an AM
device and a PM device having a mode such as PC, TN, STN, ECB, OCB,
IPS, VA, and PSA. It is especially desirable to use the composition
for an AM device having a mode of TN, OCB or IPS. These devices may
be of a reflection type, a transmission type or a semi-transmission
type. It is desirable to use the composition for a device of a
transmission type. It can also be used for an amorphous silicon-TFT
device or a polycrystal silicon-TFT device. The composition is also
usable for a nematic curvilinear aligned phase (NCAP) device
prepared by microcapsulating the composition, and for a polymer
dispersed (PD) device in which a three-dimensional net-work polymer
is formed in the composition.
[0073] It will be apparent to those skilled in the art that various
modifications and variations can be made in the invention and
specific examples provided herein without departing from the spirit
or scope of the invention. Thus, it is intended that the invention
covers the modifications and variations of this invention that come
within the scope of any claims and their equivalents.
[0074] The following examples are for illustrative purposes only
and are not intended, nor should they be interpreted to, limit the
scope of the invention.
EXAMPLES
[0075] When a sample was a composition, it was measured as it was,
and the obtained value is described here. When a sample was a
compound, a sample for measurement was prepared by mixing 15% by
weight of the compound and 85% by weight of mother liquid crystals.
A value of characteristic of the compound was calculated by
extrapolating from a value obtained by measurement. That is:
extrapolated value=(value measured-0.85.times.value for mother
liquid crystals)/0.15. When a smectic phase (or crystals) separated
out at this ratio at 25.degree. C., a ratio of the compound to
mother liquid crystals was changed step by step in the order of
(10% by weight/90% by weight), (5% by weight/95% by weight) and (1%
by weight/99% by weight), respectively. Values for a maximum
temperature, optical anisotropy, viscosity, and dielectric
anisotropy of the compound were obtained by the extrapolation.
[0076] The component of the mother liquid crystals is as shown
below. The ratio of the component is expressed by weight %.
##STR00013##
[0077] Measurement of the characteristics was carried out according
to the following methods. Most methods are described in the
Standard of Electronic Industries Association of Japan,
EIAJ.cndot.ED-2521A or those with some modifications.
[0078] Maximum Temperature of a Nematic Phase (NI; .degree. C.): A
sample was placed on a hot plate in a melting point apparatus
equipped with a polarizing microscope and was heated at the rate of
1.degree. C. per minute. A temperature was measured when part of
the sample began to change from a nematic phase into an isotropic
liquid. A higher limit of a temperature range of a nematic phase
may be abbreviated to "a maximum temperature."
[0079] Minimum Temperature of a Nematic Phase (Tc; .degree. C.): A
sample having a nematic phase was put in a glass vial and then kept
in a freezer at temperatures of 0.degree. C., -10.degree. C.,
-20.degree. C., -30.degree. C., and -40.degree. C. for ten days,
respectively, and a liquid crystal phase was observed. For example,
when the sample remained in a nematic phase at -20.degree. C. and
changed to crystals or a smectic phase at -30.degree. C., Tc was
expressed as .ltoreq.-20.degree. C. A lower limit of a temperature
range of a nematic phase may be abbreviated to "a minimum
temperature."
[0080] Viscosity (Bulk Viscosity; .eta.; measured at 20.degree. C.;
mPas): Bulk Viscosity was measured by means of an E-type
viscometer.
[0081] Viscosity (Rotational Viscosity; .gamma.1; measured at
25.degree. C.; mPas): Rotational viscosity was measured according
to the method disclosed in M. Imai, et al., Molecular Crystals and
Liquid Crystals, Vol. 259, p. 37 (1995). A sample was placed in a
TN device, in which a twist angle was 0.degree., and the cell gap
between two glass plates was 5 .mu.m. The TN device was impressed
with a voltage in the range of from 16 V to 19.5 V stepwise by 0.5
V. After a period of 0.2 second with no impress of voltage, voltage
impress was repeated with only one rectangular wave (rectangular
pulse of 0.2 second) and application of no voltage (2 seconds). A
peak current and a peak time of a transient current generated by
the voltage impress were measured. The rotational viscosity was
obtained from the measured values and the calculating equation (8)
in the article presented by M. Imai, et al., p. 40. As for the
dielectric anisotropy necessary for the calculation, the value
measured by the measuring method of dielectric anisotropy described
below with the device for measuring the rotational viscosity was
used.
[0082] Optical Anisotropy (.DELTA.n; measured at 25.degree. C.):
Measurement was carried out with an Abbe refractometer mounting a
polarizing plate on an ocular using light at a wavelength of 589
nm. The surface of a main prism was rubbed in one direction, and
then a sample was dropped on the main prism. A refractive index
(n.parallel.) was measured when the direction of polarized light
was parallel to that of the rubbing. A refractive index (n.perp.)
was measured when the direction of polarized light was
perpendicular to that of the rubbing. A value of optical anisotropy
was calculated from the equation: .DELTA.n=n.parallel.-n.perp..
[0083] Dielectric Anisotropy (.DELTA..di-elect cons.; measured at
25.degree. C.): A sample having a nematic phase was put in a TN
device having a distance between two glass plates (cell gap) of 9
.mu.m and a twist angle of 80.degree.. Sine waves (10 V, 1 kHz)
were impressed onto the device, and a dielectric constant
(.di-elect cons..parallel.) in a major axis direction of a liquid
crystal molecule was measured after 2 seconds. Sine waves (0.5 V, 1
kHz) were impressed onto the device and a dielectric constant
(.di-elect cons..perp.) in a minor axis direction of a liquid
crystal molecule was measured after 2 seconds. A value of a
dielectric anisotropy was calculated from the equation:
.DELTA..di-elect cons.=.di-elect cons..parallel.-.di-elect
cons..perp..
[0084] Threshold Voltage (Vth; measured at 25.degree. C.; V):
Measurement was carried out with an LCD Evaluation System Model
LCD-5100 made by Otsuka Electronics Co., Ltd. The light source was
a halogen lamp. A sample was poured into a TN device of a normally
white mode, in which the cell gap between two glass plates was
approximately 0.45/.DELTA.n (.mu.m), and a twist angle was
80.degree.. Voltage to be impressed onto the device (32 Hz,
rectangular waves) was stepwise increased by 0.02 volt starting
from 0 V up to 10 V. During the stepwise increasing, the device was
irradiated with light in a perpendicular direction, and the amount
of light passing through the device was measured. A
voltage-transmission curve was prepared, in which a maximum amount
of light corresponded to 100% transmittance and a minimum amount of
light corresponded to 0% transmittance. Threshold voltage was a
value at 90% transmittance.
[0085] Voltage Holding Ratio (VHR-1; measured at 25.degree. C.; %):
A TN device used for measurement had a polyimide-alignment film and
the cell gap between two glass plates was 5 .mu.m. A sample was
poured into the device, and then the device was sealed with an
adhesive polymerizable by the irradiation of ultraviolet light. The
TN device was impressed and charged with pulse voltage (60
microseconds at 5 V). Decreasing voltage was measured for 16.7
milliseconds with a High Speed Voltmeter and the area A between a
voltage curve and a horizontal axis in a unit cycle was obtained.
The area B was an area without decreasing. The voltage holding
ratio is a percentage of the area A to the area B.
[0086] Voltage Holding Ratio (VHR-2; measured at 80.degree. C.; %):
A TN device used for measurement had a polyimide-alignment film and
the cell gap between two glass plates was 5 .mu.m. A sample was
poured into the device, and then the device was sealed with an
adhesive polymerizable by the irradiation of ultraviolet light. The
TN device was impressed and charged with pulse voltage (60
microseconds at 5 V). Decreasing voltage was measured for 16.7
milliseconds with a High Speed Voltmeter and the area A between a
voltage curve and a horizontal axis in a unit cycle was obtained.
The area B was an area without decreasing. The voltage holding
ratio is a percentage of the area A to the area B.
[0087] Voltage Holding Ratio (VHR-3; measured at 25.degree. C.; %):
A voltage holding ratio was measured after irradiating with
ultraviolet light to evaluate stability to ultraviolet light. A
composition having a large VHR-3 has a large stability to
ultraviolet light. A TN device used for measurement had a
polyimide-alignment film and the cell gap was 5 .mu.m. A sample was
poured into the device, and then the device was irradiated with
light for 20 minutes. The light source was a super-high pressure
mercury lamp USH-500D (made by Ushio, Inc.), and the distance
between the device and the light source was 20 cm. In measurement
of VHR-3, decreasing voltage was measured for 16.7 milliseconds.
The VHR-3 is desirably 90% or more, and more desirably 95% or
more.
[0088] Voltage Holding Ratio (VHR-4; measured at 25.degree. C.; %):
A voltage holding ratio was measured after heating a TN device
having a sample poured therein in a constant-temperature chamber at
80.degree. C. for 500 hours to evaluate stability to heat. A
composition having a large VHR-4 has a large stability to heat. In
measurement of VHR-4, decreasing voltage was measured for 16.7
milliseconds.
[0089] Response Time (.tau.; measured at 25.degree. C.;
millisecond): Measurement was carried out with an LCD Evaluation
System Model LCD-5100 made by Otsuka Electronics Co., Ltd. The
light source was a halogen lamp. The low-pass filter was set at 5
kHz. A sample was poured into a TN device of a normally white mode,
in which the cell gap between two glass plates was 5.0 .mu.m, and a
twist angle was 80.degree.. Rectangular waves (60 Hz, 5 V, 0.5
second) were impressed to the device. During impressing, the device
was irradiated with light in a perpendicular direction, and the
amount of light passing through the device was measured. A maximum
amount of light corresponds to 100% transmittance, and a minimum
amount of light corresponds to 0% transmittance. Rise time (.tau.r;
millisecond) is the time required for a change in transmittance
from 90% to 10%. Fall time (.tau.f; millisecond) is the time
required for a change in transmittance from 10% to 90%. Response
time is the sum of the rise time and the fall time thus
obtained.
[0090] Specific Resistance (.rho.; measured at 25.degree. C.;
.OMEGA.cm): A sample of 1.0 ml was poured into a vessel equipped
with electrodes. The vessel was impressed with DC voltage (10 V)
and a direct current was measured after 10 seconds. Specific
resistance was calculated from the following equation: Specific
resistance=(voltage.times.electric capacitance of vessel)/(direct
current.times.dielectric constant in a vacuum).
[0091] Gas Chromatographic Analysis: A Gas Chromatograph Model
GC-14B made by Shimadzu Corporation was used for measurement. The
carrier gas was helium (2 ml per minute). An evaporator and a
detector (FID) were set up at 280.degree. C. and 300.degree. C.,
respectively. A capillary column DB-1 (length 30 m, bore 0.32 mm,
film thickness 0.25 .mu.m; dimethylpolysiloxane as stationary
phase, no polarity) made by Agilent Technologies, Inc. was used for
the separation of the component compound. After the column had been
kept at 200.degree. C. for 2 minutes, it was further heated to
280.degree. C. at the rate of 5.degree. C. per minute. A sample was
prepared in an acetone solution (0.1% by weight), and 1 .mu.l of
the solution was injected into the evaporator. A recorder used was
a Chromatopac Model C-R5A made by Shimadzu Corporation or its
equivalent. A gas chromatogram obtained showed the retention time
of a peak and a peak area corresponding to the component
compound.
[0092] Solvents for diluting the sample may also be chloroform,
hexane, and so forth. The following capillary column may also be
used: HP-1 made by Agilent Technologies, Inc. (length 30 m, bore
0.32 mm, film thickness 0.25 .mu.m), Rtx-1 made by Restek
Corporation (length 30 m, bore 0.32 mm, film thickness 0.25 .mu.m),
and BP-1 made by SGE International Pty. Ltd. (length 30 m, bore
0.32 mm, film thickness 0.25 .mu.m). In order to prevent compound
peaks from overlapping, a capillary column CBP1-M50-025 (length 50
m, bore 0.25 mm, film thickness 0.25 .mu.m) made by Shimadzu
Corporation may be used.
[0093] The ratio of liquid crystal compounds contained in the
composition may be calculated by the following method. The liquid
crystal compounds can be detected with a gas chromatograph. The
area ratio of each peak in the gas chromatogram corresponds to the
ratio (number of moles) of liquid crystal compounds. When the above
capillary columns are used, the correction coefficient of each
liquid crystal compound may be regarded as 1. Therefore, the ratio
of liquid crystal compounds (% by weight) is calculated from the
area ratio of each peak.
[0094] The invention will be explained in detail by way of
Examples. The invention is not limited by the Examples described
below. The compounds described in Comparative Examples and the
Examples are expressed by the symbols according to the definition
in Table 3. In Table 3, the configuration of 1,4-cyclohexylene is
trans. The parenthesized numbers next to the symbolized compounds
in the Examples correspond to the numbers of the desirable
compounds. The symbol (-) means other liquid crystal compound. The
ratios (percentage) of liquid crystal compounds are expressed by
percentage by weight (% by weight) based on the total weight of
liquid crystal compositions, and the liquid crystal compositions
contain impurities in addition to the liquid crystal compounds.
Last, the characteristics of the compositions are summarized.
TABLE-US-00003 TABLE 3 Method of Description of Compound using
Symbols. R--(A.sub.1)--Z.sub.1-- . . . --Z.sub.n--(A.sub.n)--R'
Symbol 1) Left Terminal Group R-- C.sub.nH.sub.2n+1-- n-
C.sub.nH.sub.2n+1O-- nO-- C.sub.mH.sub.2m+1OC.sub.nH.sub.2n-- mOn-
CH.sub.2.dbd.CH-- V-- C.sub.nH.sub.2n+1--CH.dbd.CH-- nV--
CH.sub.2.dbd.CH--C.sub.nH.sub.2n-- Vn-
C.sub.mH.sub.2m+1--CH.dbd.CH--C.sub.nH.sub.2n-- mVn-
CF.sub.2.dbd.CH-- VFF-- CF.sub.2.dbd.CH--C.sub.nH.sub.2n-- VFFn- 2)
Right Terminal Group --F --C.sub.nH.sub.2n+1 -n
--OC.sub.nH.sub.2n+1 --On --CH.dbd.CH.sub.2 --V
--CH.dbd.CH--C.sub.nH.sub.2n+1 --Vn
--C.sub.nH.sub.2n--CH.dbd.CH.sub.2 -nV --CH.dbd.CF.sub.2 --VFF --F
--F --Cl --CL --OCF.sub.3 --OCF3 3) Bonding group --Zn--
--C.sub.2H.sub.4-- 2 --COO-- E --CH.dbd.CH-- V --C.ident.C-- T
--CF.sub.2O-- X 4) Ring Strucure --An-- ##STR00014## H ##STR00015##
B ##STR00016## B(F) ##STR00017## B(2F) ##STR00018## B(F,F)
##STR00019## B(2F,5F) ##STR00020## Py ##STR00021## G 5) Example of
Description Example 1 V2-BB(F)B-1 ##STR00022## Example 2 3-HB-CL
##STR00023## Example 3 5-PyBB-F ##STR00024## Example 4
3-BB(F,F)XB(F)-OCF3 ##STR00025##
Comparative Example 1
[0095] Example 39 was selected from among compositions disclosed in
WO 1966-011897 A. The basis for the selection was because the
composition contained the compound (3) and had the smallest
rotational viscosity. Since there was no description about the
rotational viscosity, the composition was prepared to measure the
rotational viscosity according to the method described above. The
composition had the following components and characteristics.
TABLE-US-00004 3-HBXB(F,F)-F (3) 3% 5-HBXB(F,F)-F (3) 8%
3-HBXB-OCF3 (3) 5% 2-HBB(F)-F (3) 8% 3-HBB(F)-F (3) 8% 5-HBB(F)-F
(3) 16% 5-HB-F (3) 6% 7-HB-F (3) 6% 5-HHB-OCF3 (3) 8% 3-H2HB-OCF3
(3) 8% 5-H2HB-OCF3 (3) 8% 3-HH2B-OCF3 (3) 8% 5-HH2B-OCF3 (3) 8% NI
= 84.9.degree. C.; .DELTA.n = 0.101; .DELTA..epsilon. = 5.5; Vth =
2.12 V; .eta. = 16.6 mPa s; .gamma.1 = 110 mPa s.
Comparative Example 2
[0096] Example 4 was selected from among compositions disclosed in
JP 2003-176251 A. The basis for the selection was because the
composition contained the compounds (3-5-1), (3-6-1) and (3-9-1),
and had the smallest rotational viscosity. Since there was no
description about the rotational viscosity at 25.degree. C., the
composition was prepared to measure the rotational viscosity
according to the method described above. The composition had the
following components and characteristics.
TABLE-US-00005 2-HHB(F,F)-F (3-5-1) 12% 3-HHB(F,F)-F (3-5-1) 10%
2-HHB-OCF3 (3) 8% 3-HHB-OCF3 (3) 8% 4-HHB-OCF3 (3) 7% 5-HHB-OCF3
(3) 4% 2-HB(F)B(F,F)-F (3) 12% 3-HB(F)B(F,F)-F (3) 4% 2-HHXB(F,F)-F
(3-6-1) 12% 2-BB(F)B(F,F)-F (3-9-1) 8% V-HHXB(F,F)-F (3) 15% NI =
75.0.degree. C.; .DELTA.n = 0.093; Vth = 1.17 V; .gamma.1 = 115 mPa
s.
Example 1
[0097] It was found that the composition of Example 1 had a smaller
rotational viscosity than that of Comparative Example 1.
TABLE-US-00006 5-HHB(F)HXB(F,F)-F (1-1-1-1) 5% V-HH-3 (2-1-1) 36%
1V-HH-3 (2-1-1) 11% V-HHB-1 (2-4-1) 11% V2-HHB-1 (2-4-1) 3%
2-BB(F)B-3 (2-6-1) 10% 2-BB(F)B-5 (2-6-1) 2% 3-HBB(F,F)-F (3-8-1)
6% 3-BB(F,F)XB(F,F)-F (3-11-1) 16% NI = 77.9.degree. C.; Tc
.ltoreq. -20.degree. C.; .DELTA.n = 0.104; .DELTA..epsilon. = 3.1;
Vth = 2.58 V; .gamma.1 = 43.9 mPa s; .tau. = 7.8 ms; VHR-1 = 99.1%;
VHR-2 = 98.2%; VHR-3 = 98.1%.
Example 2
[0098] It was found that the composition of Example 2 had a smaller
rotational viscosity than that of Comparative Example 1.
TABLE-US-00007 5-HHB(F)HXB(F,F)-F (1-1-1-1) 5% 5-GHB(F)HXB(F,F)-F
(1-1-2-1) 5% V-HH-3 (2-1-1) 40% 1V-HH-3 (2-1-1) 11% 2-BB(F)B-3
(2-6-1) 7% 1-BB(F)B-2V (2-6-1) 6% 2-BB(F)B-2V (2-6-1) 6%
3-HBB(F,F)-F (3-8-1) 3% 3-BB(F,F)XB(F,F)-F (3-11-1) 17% NI =
76.2.degree. C.; Tc .ltoreq. -20.degree. C.; .DELTA.n = 0.108;
.DELTA..epsilon. = 3.4; Vth = 2.10 V; .gamma.1 = 52.1 mPa s; .tau.
= 8.9 ms; VHR-1 = 99.2%; VHR-2 = 98.3%; VHR-3 = 98.2%.
Example 3
[0099] It was found that the composition of Example 3 had a smaller
rotational viscosity than that of Comparative Example 1.
TABLE-US-00008 5-HHB(F)HXB(F,F)-F (1-1-1-1) 5% 5-GHB(F)HXB(F,F)-F
(1-1-2-1) 5% 5-HGB(F)HXB(F,F)-F (1-1-3-1) 5% V-HH-3 (2-1-1) 42%
1V-HH-3 (2-1-1) 11% V2-BB-1 (2-3-1) 6% V-HHB-1 (2-4-1) 5% 3-HB-CL
(3-1-1) 3% 3-BB(F,F)XB(F,F)-F (3-1 1-1) 10% 3-BB(F)B(F,F)XB(F,F)-F
(3-17-1) 4% 4-BB(F)B(F,F)XB(F,F)-F (3-17-1) 4% NI = 79.0.degree.
C.; Tc .ltoreq. -20.degree. C.; .DELTA.n = 0.092; .DELTA..epsilon.
= 4.2; Vth = 2.00 V; .gamma.1 = 61.1 mPa s; .tau. = 7.2 ms; VHR-1 =
99.2%; VHR-2 = 98.3%; VHR-3 = 98.2%.
Example 4
[0100] It was found that the composition of Example 4 had a smaller
rotational viscosity than that of Comparative Example 2.
TABLE-US-00009 5-HGHXB(F)B(F,F)-F (1-2-1-1) 10% V-HH-3 (2-1-1) 30%
1V-HH-3 (2-1-1) 10% V-HH-4 (2-1-1) 7% V-HBB-1 (2-5-1) 10%
1-BB(F)B-2V (2-6-1) 5% 3-HHXB(F,F)-F (3-6-1) 5% 3-BB(F,F)XB(F,F)-F
(3-11-1) 5% 3-BB(F,F)XB(F)-OCF3 (3-12-1) 5% 3-BB(F)B(F,F)XB(F,F)-F
(3-17-1) 5% 4-BB(F)B(F,F)XB(F,F)-F (3-17-1) 8% NI = 79.1.degree.
C.; Tc .ltoreq. -20.degree. C.; .DELTA.n = 0.105; .DELTA..epsilon.
= 8.2; Vth = 1.31 V; .gamma.1 = 98.7 mPa s; .tau. = 15.9 ms; VHR-1
= 99.2%: VHR-2 = 98.3%: VHR-3 = 98.2%.
Example 5
TABLE-US-00010 [0101] 5-HHB(F)HXB(F,F)-F (1-1-1-1) 5%
5-HB(F)HHXB(F,F)-F (1-1-4-1) 5% 2-HH-3 (2-1-1) 10% 3-HH-4 (2-1-1)
15% 3-HB-O2 (2-2-1) 6% 3-HHB-1 (2-4-1) 5% 2-BB(F)B-3 (2-6-1) 5%
2-BB(F)B-5 (2-6-1) 5% 3-BB(F)B-5 (2-6-1) 5% 5-HB-CL (3-1-1) 10%
3-HHB-CL (3-4-1) 5% 3-HHB(F,F)-F (3-5-1) 9% 5-BB(F,F)XB(F,F)-F
(3-11-1) 15% NI = 81.2.degree. C.; Tc .ltoreq. -20.degree. C.;
.DELTA.n = 0.113; .DELTA..epsilon. = 4.2; Vth = 2.30 V; .gamma.1 =
53.6 mPa s; .tau. = 5.9 ms; VHR-1 = 99.1%; VHR-2 = 98.1%; VHR-3 =
98.1%.
Example 6
TABLE-US-00011 [0102] 5-HGHXB(F)B(F,F)-F (1-2-1-1) 10%
5-HHHXB(F)B(F,F)-F (1-2) 5% V-HH-3 (2-1-1) 37% V2-BB(F)B-1 (2-6-1)
5% 3-HB-CL (3-1-1) 17% 1V2-BB-F (3-2-1) 5% 1V2-BB-CL (3-3-1) 5%
3-PyBB-F (3-10-1) 7% 4-PyBB-F (3-10-1) 7% 5-PyBB-F (3-10-1) 2% NI =
80.8.degree. C.; Tc .ltoreq. -20.degree. C.; .DELTA.n = 0.121;
.DELTA..epsilon. = 3.0; Vth = 2.17 V; .gamma.1 = 54.2 mPa s; .tau.
= 6.5 ms; VHR-1 = 99.2%; VHR-2 = 98.2%; VHR-3 = 98.2%.
Example 7
TABLE-US-00012 [0103] 5-HHB(F)HXB(F)-OCF3 (1-1-1) 5%
5-GHB(F)HXB(F)-OCF3 (1-1-2-2) 5% V-HH-3 (2-1-1) 42% 1V-HH-3 (2-1-1)
5% 3-HHXB(F,F)-F (3-6-1) 10% 3-BB(F,F)XB(F,F)-F (3-11-1) 5%
3-BB(F,F)XB(F)-OCF3 (3-12-1) 5% 4-HBB(F,F)XB(F,F)-F (3-15-1) 5%
4-HB(F)B(F,F)XB(F,F)-F (3-16-1) 5% 4-BB(F)B(F,F)XB(F,F)-F (3-17-1)
5% 3-HHXB(F)-OCF3 (3-18) 3% 3-BB(F,F)XB(F)-F (3-19) 5% NI =
76.0.degree. C.; Tc .ltoreq. -20.degree. C.; .DELTA.n = 0.095;
.DELTA..epsilon. = 8.1; Vth = 1.34 V; .gamma.1 = 89.7 mPa s;; VHR-1
= 99.0%; VHR-2 = 98.2%; VHR-3 = 98.1%.
Example 8
TABLE-US-00013 [0104] 5-HHB(F)HXB(F,F)-F (1-1-1-1) 5% V-HH-3
(2-1-1) 47% 3-HBB-2 (2-5-1) 5% 3-HBB-F (3-7-1) 5% 2-BB(F)B(F,F)-F
(3-9-1) 5% 3-BB(F)B(F,F)-F (3-9-1) 10% 3-BB(F,F)XB(F,F)-F (3-11-1)
10% 3-HHBB(F,F)-F (3-13-1) 4% 3-HHB(F)B(F,F)-F (3-14-1) 4% 1O1-HH-3
(-) 5% NI = 85.5.degree. C.; Tc .ltoreq. -20.degree. C.; .DELTA.n =
0.108; .DELTA..epsilon. = 4.2; Vth = 2.10 V; .gamma.1 = 72.8 mPa s;
.tau. = 10.9 ms; VHR-1 = 99.0%; VHR-2 = 98.1%; VHR-3 = 98.2%.
Example 9
TABLE-US-00014 [0105] 5-GHB(F)HXB(F,F)-F (1-1-2-1) 5%
5-HGB(F)HXB(F,F)-F (1-1-3-1) 5% 5-HGHXB(F)B(F,F)-F (1-2-1-1) 5%
V-HH-3 (2-1-1) 42% 1V-HH-3 (2-1-1) 5% V-HHB-1 (2-4-1) 3% 3-HBB-F
(3-7-1) 5% 3-HGB(F,F)-F (3-22) 5% 4-HGB(F,F)-F (3-22) 5%
5-HGB(F,F)-F (3-22) 5% 3-GHB(F,F)-F (3-23) 5% 4-GHB(F,F)-F (3-23)
5% 5-GHB(F,F)-F (3-23) 5% NI = 83.6.degree. C.; Tc .ltoreq.
-20.degree. C.; .DELTA.n = 0.075; .DELTA..epsilon. = 4.6; Vth =
1.99 V; .gamma.1 = 80.7 mPa s; .tau. = 14.7 ms; VHR-1 = 99.1%;
VHR-2 = 98.1%; VHR-3 = 98.1%
Example 10
TABLE-US-00015 [0106] 5-HHB(F)HXB(F,F)-F (1-1-1-1) 5%
5-HB(F)HHXB(F,F)-F (1-1-4-1) 5% 3-HH-VFF (2-1) 21% 5-HH-VFF (2-1)
21% V-HHB-1 (2-4-1) 8% 5-HB-CL (3-1-1) 5% 3-HHB(F,F)-F (3-5-1) 5%
3-HBB(F,F)-F (3-8-1) 5% 3-HHEB(F,F)-F (3-20) 10% 3-HBEB(F,F)-F
(3-21) 5% 4-HBEB(F,F)-F (3-21) 5% 5-HBEB(F,F)-F (3-21) 5% NI =
83.4.degree. C.; Tc .ltoreq. -20.degree. C.; .DELTA.n = 0.088;
.DELTA..epsilon. = 4.6; Vth = 1.97 V; .gamma.1 = 74.1 mPa s; .tau.
= 13.2 ms; VHR-1 = 99.1%; VHR-2 = 98.1%; VHR-3 = 98.1%.
[0107] Although the invention has been described and illustrated
with a certain degree of particularity, it is understood that the
disclosure has been made only by way of example, and that numerous
changes in the conditions and order of steps can be resorted to by
those skilled in the art without departing from the spirit and
scope of the invention.
* * * * *